Last I heard was August. Though there is a rumor of it being delayed. Mojang is horrible at communicating with people so who knows. Apparently the worlds are going to be 36x larger than the 360 edition's.
The 360's worlds were already able to occupy a whole map, so that's gonna be awesome. I really hope they open up the game a bit more than the 360 as well, I wanna import my PC world and texture packs. -3-